Field of the Invention
The present invention relates to a telephoto lens and an image pickup apparatus using the same. The present invention, in particular, relates to a telephoto lens which is most suitable as an interchangeable lens system application.
Description of the Related Art
In recent years, with the development of digital cameras, various interchangeable lenses for digital cameras have been proposed. For instance, in Japanese Patent Application Laid-open Publication No. 2007-322986, a three-unit arrangement which comprises a positive unit, a negative unit, and a positive unit is disclosed. In this arrangement, a stop is disposed nearest to an image in a first unit, and focusing on an object point at a short distance is carried out by moving a second unit. By making such arrangement, a telephoto lens of 300 mm/F4 for an interchangeable lens application is realized.
Moreover, in Japanese Patent Application Laid-open Publication No. 2013-250293 for instance, a three-unit arrangement which comprises a positive unit, a negative unit, and a positive unit is disclosed. In this arrangement, the focusing is carried out by moving a second unit, and a stop is disposed in a third unit. By making such arrangement, a telephoto lens of a range from 400 mm/F2.8 to 800 mm/F5.6 is realized.